1. Field of the Invention
This invention relates to a copy medium carrier which permits one-side printing and both-side printing to be selectively effected on conventional copy mediums, instead of one-side printing only
2. Description of the Prior Art
Conventional copying machines have generally been of the one-side printing type in which only one-side printing is effected on copy mediums. According to such conventional method, however, the number of copies produced is double the number of copies produced by the both-side printing system and, where a huge quantity of copies is to be stored, this has been disadvantageous in terms of storage space, weight, cost, etc. The present invention intends to eliminate these disadvantages peculiar to the one-side printing and to provide a copy medium carrier which permits the both-side printing to be effected as well.
Several types of copying apparatus capable of both-side printing have heretofore been considered. A first of them is the type which employes two photosensitive drums for forming thereon discrete images to be transferred to the opposite sides of copy medium, respectively. This type is simple in principle but involves two sets of copying processes, which leads to a high cost and large scale of the apparatus. A second type is that in which an image to be transferred to one side of copy medium is first formed on a photosensitive drum and such image is transferred to an intermediary drum for temporal preservation, whereafter an image to be transferred to the other side of the copy medium is formed again on the photosensitive drum, and then these images are transferred from the intermediary drum and the photosensitive drum to the respective sides of the copy medium. The system requires only one set of copying process, but involves two cycles of image transfer through the intermediary drum and this means a reduced efficiency of image transfer. In a third type, ordinary one-side printing is effected on one side of copy medium, whereafter such one-side printed copy medium is again directed to the copy medium feed means or to a second feed means, from which the copy medium is fed in up-side-down fashion into the copying apparatus so that ordinary one-side printing is effected on the other side of the copy medium. This third type involves only one set of copying processes as in the case of one-side printing and may be said to be an economical and compact copying apparatus which can perform both-side printing in the most practical manner, as compared with the first or the second type which has disadvantages of expensiveness or large scale of the apparatus or reduced efficiency of image transfer, as noted above.
Where both-side printing is to be effected with a cassette system copying machine as the third type, it has heretofore been the practise that a copy medium discharged with one side thereof printed is placed into another carrier (cassette or the like) for the other side of the copy medium to be printed, and then the previously used cassette is removed from te copying machine and replaced by said another carrier so that the other side of the copy medium may undergo one-side printing similar to the previous one. However, wher it is desired to obtain a few copies of various originals by both-side printing, the cassette loading and unloading must be effected frequently and the cassette replacement involves cumbersome procedures, and this also offers a problem as to the service life of the cassettes.
Further, according to the conventional system, different cassettes respectively containing therein different sizes of copy mediums are prepared and one of these cassettes may be loaded into the feed means of the copying machine or the like. Although such system is efficient in that replacement of copy mediums can easily be done by replacement of the cassettes, a plurality of cassettes must be prepared for respective sizes of copy mediums and a space is required for the storage of these cassettes, but this has been undesirable from the standpoint of moisture-proof or dust-proof effect and also has involved cumbersome procedures or troubles in operation.
In the conventional carrier (cassette), loading of the carrier with copy mediums or the like has been done by depressing a carrying portion for carrying copy mediums or the like to widen the spacing between such carrying portion and a separating portion for separating the copy mediums so as to permit the copy mediums to be inserted into between the two portions, whereas the spacing between the separating portion and the copy medium carrying portion has not been sufficiently wide with respect to a posible full load of copy mediums so that the loading operation has not been easy.
More specifically, in case of the conventional carrier, a load of copy mediums is inserted into the carrier in accordance with a reference mark provided on the rear side of an inner plate. At this time, the leading end of the load of copy mediums rests on a separator pawl. If the load of copy mediums is then depressed in the center portion thereof, the inner plate is also lowered to cause the leading end of the load of copy mediums to come beneath the separator pawl due to the self-supporting action of the load of copy mediums, so that the load rests on the inner plate. When the force imparted to the center portion of the load of copy mediums is released, the inner plate and accordingly the load thereon is raised by the force of springs until the load of copy mediums and the separator pawl hitherto lowered to its lowermost position reach their uppermost positions, whereupon the loading completes.
In such conventional carrier, the above-described self-supporting action of the load of copying mediums would offer no problem if there is a great spacing between the separator pawl in its lowermost position and the upper side of the load of copy mediums when the load has been depressed, but difficulties would be encountered if the load of copy mediums is increased and the spacing decreased.